This proposal will be an investigation of respiratory syncytial (RS) virus polypeptide synthesis. The kinetics of viral polypeptides synthesized in cells infected at high multiplicity (5-10 PFU/cell) will be followed by pulse-labeling and pulse-chase experiments. Acetone precipitated and immunoprecipitated viral polypeptides will be analyzed on polyacrylamide slab gels. Comparisons of virion structural polypeptides with in vivo and in vitro translation products will be made and correlation of infected cell proteins with cell-free products will be carried out by peptide mapping and immunoprecipitation with monospecific antibodies. Intracellular nucleocapsids will be analyzed so that proteins associated with viral RNA throughout the infectious cycle can be identified and compared with the proteins of virion nucleocapsids. Phosphorylationof viral proteins will be studied in infected cells and in purified virions. Experiments designed to isolate and purify virion glycoproteins will be carried out so that monospecific antisera can be made. Monospecific antibodies will be used to determine the biological functions of the glycoproteins in the infectious process. The information gained from these experiments may (1) benefit the development of viral or subviral component vaccines as well as (2) improve diagnostic techniques. Immunological and electrophoretic techniques will be utilized to attempt to determine differences in the polypeptides of various strains of RS virus.